At about 6 months, most babies can sit independently, so that’s when you can put them into the high chair. Some are ready earlier and some later. But remember to buckle them up:) My LO fell off the high chair before. That was quite traumatic.
Depending on what highchair are you getting. If you get like stokke or oribel, it can be full Inclined, it can be used from 2-3months
Most recommend waiting until a baby is 6 months old before using a high chair.
When baby can sit independently unsupported
6 months or when he can support his neck.
my baby can sit 5 months unsupported.
I started around 6 months
Better after 6 months
Between 4 to 6 months
6 month at least